An ideal composition for delivery of a topically-active compound to skin or hair is phase stable and delivers the topically-active compound such that it adheres to the skin or hair while topically-inactive ingredients evaporate or are otherwise removed from the application site. Topically-delivered active compounds, such as an antiperspirant compound, skin care compound or topical medicament, conventionally have been prepared as either oil-in-water emulsions or water-in-oil emulsions. However, prior topically-effective compositions prepared as emulsions typically felt wet when applied to the skin. In addition, many emulsion-type compositions leave a white, staining residue on contacted skin or clothing.
For example, antiperspirant compositions are available in a variety of forms, such as aerosol suspensions; pump sprays; roll-on powders; emulsions or suspensions; and solid gels, waxes or suspensions. Emulsified antiperspirant compositions of these various forms are well-known in the cosmetic art. Antiperspirant compositions prepared as either oil-in-water emulsions or water-in-oil emulsions typically have a milky or opaque appearance and are manufactured by complex methods. An ideal emulsified antiperspirant composition is stable for the life of the composition, effectively delivers the antiperspirant compound to the skin, does not leave a visually-observable white residue on the skin or clothing, and is esthetically pleasing to the consumer.
Roll-on and gelled emulsion-type topically-effective compositions are used by rubbing an area of the body, such as the underarm, to apply a layer of the composition to the skin. Roll-on and gel topically-effective compositions preferably possess the esthetic properties of smoothness, nonoiliness and nontackiness. The topically-effective compositions should not have a wet feeling. Clarity, or transparency, of topically-effective compositions also is a long-sought desirable esthetic property. Another highly desirable, but hard to achieve, esthetic property is avoiding a visible residue, e.g., a white layer, that is left on the skin clothing after the topically-effective composition is applied.
Nonemulsified topically-effective compositions also are known in the art but demonstrate serious disadvantages. Nonemulsified compositions often require shaking prior to each use in order to redisperse the insoluble topically-active compound that has separated from the composition. Nonemulsified topically-effective compositions that do not require shaking prior to each use, such as an antiperspirant creme or paste, typically include a relatively high percentage of suspending agents, like an organoclay. The presence of an organoclay in an antiperspirant composition is a principal source of whitening and staining skin and clothing.
Investigators have searched for topically-effective compositions, and especially transparent antiperspirant compositions, that overcome the above-described disadvantages. A roll-on antiperspirant however is difficult to formulate and manufacture because the composition requires a sufficient viscosity to adhere to the skin and resist dripping off or running down the skin, and yet is not tacky or sticky. A gel antiperspirant composition is difficult to formulate and manufacture because of formulation parameters such as firmness, viscosity control, lack of syneresis and nontackiness. Transparent, roll-on or gel antiperspirant compositions are more difficult to formulate because of the added requirement of transparency.
A transparent roll-on or gel antiperspirant composition which has consumer-acceptable esthetic and functional properties is highly desired commercially. Transparent antiperspirant compositions, especially in the roll-on or gel form, are particularly favored by consumers because such transparent products are esthetically appealing and project the appearance of product purity, safety, good performance and being non-whitening. However, providing a commercially-acceptable, transparent roll-on or gel antiperspirant composition requires overcoming several formulation and manufacturing problems.
Similarly, other roll-on or gel topically-effective compositions, especially transparent compositions, which include a topically-active compound are not readily available due to the identical formulation problems encountered in the manufacture of a roll-on or gel antiperspirant composition. Topically-effective compositions, such as skin care products, suntan lotions, topical medicaments and sunscreens, require many of the same esthetic and functional properties as an antiperspirant composition. Therefore, overcoming the formulation and manufacturing problems associated with roll-on or gel antiperspirant compositions also overcome many of the problems associated with other, related topically-effective compositions. The following discussion, which is directed primarily to antiperspirant compounds, therefore similarly is directed to gel or roll-on topically-effective compositions in general.
Solid antiperspirant compositions are divided into three main classes, i.e., compressed powder sticks, gel sticks and wax sticks. Each of these classes has advantages, but each class also has particular disadvantages. Compressed powder sticks for example frequently are brittle and hard, and leave a cosmetically-unacceptable powdery residue after application. Wax-based products often are cosmetically unacceptable because of hardness, greasiness and tackiness. The opacity of wax sticks and the visually-observable white residue remaining after application also are esthetically undesirable.
Gel-type solid antiperspirant compositions have several advantages over both compressed powder sticks and wax sticks. For example, gel antiperspirant compositions leave less residue or dust on the skin. Gel antiperspirant compositions also glide easily over the skin surface resulting in an easy and comfortable application of the composition.
Prior transparent, gel antiperspirant compositions also typically were divided into three main classes. One of these classes is the optically-clear gelled emulsion compositions. These compositions include a water phase and an oil phase. The oil phase often is suspended in the water phase (i.e., an oil-in-water emulsion) by using a sufficient amount of an appropriate emulsifier or emulsifiers. Oil-in-water emulsion products have a wet feel because the continuous external phase is aqueous. Water-in-oil emulsions, wherein the continuous external phase is organic in nature, also are known. The emulsions conventionally contained waxes, silicones, clays and emollients. Gelled emulsion compositions, including optically-clear compositions, are illustrated in U.S. Pat. Nos. 4,673,570, 4,268,499, and 4,350,605; and in "Deodorant and Antiperspirant Formulary", Cosmetics & Toiletries, Dec. 12, 1985, vol. 100, p. 65-75.
The optically-clear gelled emulsion compositions often exhibit the disadvantages of composition instability during storage; the development of a hazy or milky appearance during storage; a stringy, tacky, oily consistency and other undesirable esthetic properties. In addition, the emulsion gel compositions often leave a visible residue on the skin or clothing in the form of a white layer.
Another disadvantage of optically-clear gelled emulsion compositions is the complex method of preparing an optically-clear gelled emulsion composition. The method traditionally requires high shear rates during mixing, high processing temperatures, and a series of cooling and heating process steps. In one embodiment of the present invention, optically-clear gel-like emulsion compositions are prepared by a simple refractive index matching technique to provide topically-effective compositions that overcome the above-described disadvantages of prior optically-clear gelled emulsion compositions.
The problems associated with gel antiperspirants can be partially overcome by formulating a roll-on antiperspirant. Roll-on antiperspirants typically are viscous liquids to semi-solids However, roll-on antiperspirants often impart a tacky feel and still have a tendency to leave an unsightly white residue on the skin.
Numerous patents and publications disclose attempts to provide a consumer-acceptable, roll-on or gel topically-effective composition, and especially an antiperspirant composition. EP 0 396 137 discloses a transparent, anhydrous antiperspirant composition wherein transparency is accomplished by matching the refractive index of the anhydrous vehicle with a particulate antiperspirant compound. EP 0 435 483 discloses a water-in-oil silicone emulsion including an alkane diol and an inorganic electrolyte. WO 91/08732 and WO 92/05767 disclose emulsified, water-in-oil antiperspirant compositions having a viscosity of less than about 1,000 cps (centipoise) or at least about 50,000 cps, respectively. U.S. Pat. Nos. 4,311,695, 4,980,156, 4,988,504 and 5,066,756 disclose opaque, water-in-oil antiperspirant emulsions. Each reference relies upon a silicon-containing emulsifier to provide the water-in-oil emulsion.
U.S. Pat. No. 4,948,578 discloses optically clear antiperspirant sticks comprising up to 50% water and a surfactant having a high HLB value. U.S. Pat. No. 5,258,174 also discloses clear stick antiperspirant compositions. U.S. Pat. No. 4,499,069 discloses an antiperspirant composition having a specific combination of a high HLB surfactant and a low HLB surfactant to provide a surfactant blend having an HLB of about 7.5 to less than 9.9. U.S. Pat. No. 5,216,033 discloses a transparent water-in-oil emulsion prepared from a silicone surfactant, wherein the refractive index is matched using a polyhydric alcohol. U.S. Pat. No. 4,944,938 discloses a transparent antiperspirant gel including only 15% to 20% water.
GB 2,079,300 discloses transparent silicone-containing oil-in-water emulsions prepared by the addition of a polyol. The emulsions include high HLB surfactants. U.S. Pat. No. 4,784,844 discloses oil-in-water opaque to transparent silicone emulsions including up to 80% internal phase. Other patents disclosing silicone-containing oil-in-water emulsions include U.S. Pat. Nos. 4,122,029, 4,732,754, and 5,162,378. Patents disclosing silicone surfactants used in topically-effective compositions include U.S. Pat. Nos. 4,988,504 and 5,008,103.
Other patents and publications disclosing emulsified antiperspirant compositions include U.S. Pat. Nos. 4,695,451 and 4,650,671; EP 0 295 070 and EP 0 448 278; R. L. Golemberg et al., "Silicones in Clear Formulations", D&CI, February, 1986, pages 34, 38, 40 and 44; and N. Garti et al., "Transparent Microemulsions for Cosmetic Preparations", Internat. J. Cosmet. Sci., 8, pp. 1-8 (1986).
Although numerous patents disclose transparent antiperspirant compositions, the compositions designated as clear or transparent often lack the clarity or the dry feel desired by consumers. Some transparent antiperspirant compositions also exhibit an unacceptable degree of syneresis, or phase separation, during storage. Moreover, many of the prior art transparent compositions become cloudy or hazy after standing for a period of time. Typically, haziness increases to such an extent that the composition is cloudy and has little or no transparency about a month after preparation. Antiperspirant compositions conventionally have a product life in excess of one month. Therefore, the length of time the composition retains its transparency is an important esthetic property.
Investigators continually have sought to provide emulsion-type roll-on or gel topically-effective compositions having both long-term stability and sufficient esthetic and functional properties for consumer acceptance. These esthetic and functional properties include transparency, no visually-observable whitening of the skin and clothing, and the ability to effectively deliver the topically-active compound to the skin without irritating the skin or imparting a tacky or sticky feeling. The present invention is directed to providing roll-on or gel topically-effective compositions, and preferably transparent compositions, exhibiting these consumer-acceptable esthetic and functional properties.